Students in the running for National Merit finalist status have always been required to submit SAT scores. Thus those who fared well on the ACT still needed to sit for the SAT, too, if they expected to climb the National Merit ladder.
But starting with the 2020 National Merit competition, students hoping to advance from semi-finalist to finalist can take either the SAT or the ACT, which is a big change that a lot of folks have wanted for a long time.
Although I've long believed that, for the majority of teenagers (and their parents), there's way more ballyhooing over National Merit than it deserves, this is still a milestone worth noting. In particular, it could help to provide scholarship money to good students with bad counseling.
See #10 for more details: https://www.nationalmerit.org/s/1758/interior.aspx?sid=1758&gid=2&pgid=434